Reusable Mud-Sill

ABSTRACT

A reusable mud-sill to replace the conventional wooden-mud-sills and to capture without the use of tools the small-metal-plate conventionally found at the bottom of scaffold legs. Mud-sills are used to interface the bottom ends of scaffold legs, or the like, to the ground and to provide reasonable ground pressure while inhibiting side movement of a leg. The reusable mud-sill captures a small-metal-plate with two fixed opposing side-blocks, a fixed overlapping-retainer, and a sliding overlapping-retainer that may be locked to the reusable mud-sill when the conventional small-metal-plate has been captured. The cooperating, capturing parts are all centrally placed on the top of a flat-plate that is significantly larger than the small-metal-plate.

REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application 61/137,450 filed Jul. 31, 2008, which is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The technical field of the present invention is the field of mud-sills. Mud-sills are most often associated with scaffolding. The vertical and diagonal supports of scaffolding react their longitudinal force into the supporting ground. Most often, the ends of the supports are terminated with a screw (or like means for adjusting height) attached to a small-metal-plate. To distribute the force into a reasonable ground pressure, and to conform to 29 CFR 1926.451 (c)(2) and similar state requirements, the small-metal-plate found at the bottom end of scaffold legs is nailed to the top of a wooden board that contacts the ground. The wooden board is called a mud-sill.

The subject of this invention is an improved, reusable mud-sill that provides enhanced safety and that provides significant cost savings as compared to present wooden board mud-sills. The present invention's reusable mud-sill is intended to replace the conventional wooden-mud-sills. More particularly, the mud-sill of the present invention is able to capture the small-metal-plate without the use of tools and without the use of a wooden board, and is able to be reused many times. While the present invention is expected to have its major utility in conjunction with scaffolding, the present invention will also have utility with ladders and the like where their ground termination must not shift. The present invention makes use of the small-metal-plate that is most often essentially six inches square and that is conventionally found at the bottom end of scaffold legs. The present invention is also useful with small-metal-plates that are essentially five inches square.

2. Background Art

FIG. 1 illustrates the prior-art. Three different linkages between scaffolding (not shown) and wooden-mud-sill 1 are shown on FIG. 1. In most cases, scaffold-legs are essentially normal to small-metal-plate 10 as shown in the bottom two sub-figures of FIG. 1. In one of those cases, fixed-scaffold-leg 14 is affixed directly to small-metal-plate 10 with a height-adjuster 18 being provided or, in the other case, fixed-scaffold-leg 14 is connected to small-metal-plate 10 by means of fixed-leg-coupler 12 with height-adjuster 18 being provided. The latter scheme of attachment of a fixed-scaffold-leg 14 to small-metal-plate 10 is also seen on FIGS. 2 & 3. A variation, seen on the upper sub-figure of FIG. 1, uses a pivotable-scaffold-leg 15 that uses cross-piece 16 within bushing 17 to provide for other than normal attachment to small-metal-plate 10. The latter scheme of attachment of pivotable-scaffold-leg 15 to small-metal-plate 10 is also seen on FIG. 4.

In each type of attaching a scaffold-leg to small-metal-plate 10, the prior art includes nailing small-metal-plate 10 to wooden-mud-sill 1. Scaffold-legs are usually threaded to facilitate manually adjusting the scaffold-leg's height using height-adjuster 18. Information similar to that shown on FIG. 1 may be seen within FIG. 7 of U.S. Pat. No. 5,156,235.

A significant limitation of the prior-art involves the wooden boards that are used as mud-sills. Firstly, to be effective, the wooden boards must be fairly thick and long. Hence, the necessarily heavy wooden boards are awkward to transport and to wrestle into place. Secondly, the contact of the wooden boards with the ground causes than to absorb moisture, which increases their weight and which hastens their rotting. Thirdly, the tendency of the boards to rot and to be mud covered reduces the likelihood of being reused, which adversely impacts the cost of using wooden boards. Fourthly, having to nail the small-metal-plates to the wooden boards, and the accompanying need to remove the nails when moving the attendant scaffold, results in a significant labor and material cost.

Among the objectives of the present invention is the objective to overcome the listed limitations of the use of wooden board mud-sills. More specifically: the present invention is easy to transport and to place into position. It requires negligible effort, and no tools, to have the present invention capture small-metal-plates. Additionally, the present invention is expected to last for many years resulting in its expected amortized cost to be less than the alternatives and the use of the present invention eliminates the need to have a stock of nails and hammers, effecting further value.

BRIEF SUMMARY OF THE INVENTION

The preferred embodiment of the present invention is seen on the drawings as reusable mud-sill 30. The preferred embodiment is made of steel although other materials would also be suitable. The invention captures a standard, six inch by six inch small-metal-plate 10, found at the bottom of scaffolding, by inserting the small-metal-plate between side-blocks 22 and into front-overlapping-retainer 24 with the moveable-rear-overlapping-retainer 32 slid as far from the center of mud-sill 30 as allowed by the retaining-pins that are captive in retaining-pin's grooves 36. The moveable-rear-overlapping-retainer 32 is then slid towards the center so that the small-metal-plate is captured. Locking-lever 38 is rotated into a mating groove, thus locking the small-metal-plate in place.

Optionally, the reusable mud-sill 30 may have its resistance to side movement enhanced by inserting spikes 40 into spike-holes 42 that are provided in the corners of the reusable mud-sill 30. The spikes 40 are easily retracted with minimal damage when it is time to move mud-sill 30.

When it is time to move the associated scaffolding, locking-lever 38 is rotated out of its groove, moveable-rear-overlapping-retainer 32 is slid away, and the small-metal-plate 10 is free. The reusable mud-sill 30 may now be moved to a new location or stored for future use. All of this is accomplished without the use of tools.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows the prior art of nailing small-metal-plates to a wooden board mud-sill. Three conventional attachments of scaffold legs to small-metal-plates are shown.

FIG. 2 shows the preferred embodiment of the present invention in an un-locked state with a small-metal-plate in the process of being captured.

FIG. 3 shows the preferred embodiment of the present invention in a locked state with a small-metal-plate captured by the present invention.

FIG. 4 shows the preferred embodiment of the present invention in a locked state with a small-metal-plate that has a pivotable-scaffold-leg.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 2 and 3 advantageously show the preferred embodiment of the present invention. Reusable mud-sill 30 is made of steel and has permanently affixed to it side-blocks 22 and front-overlapping-retainer 24. Since the reusable mud-sill 30 will be in contact with the earth, it is anticipated that it might advantageously be composed of marine-brass, stainless-steel, or of a strong plastic. The latter materials are expected to be more expensive than steel, but are also expected to be much more resistant to corrosion than is steel. It is advantageous to paint all of the present invention with a corrosion resistant paint.

Side-blocks 22 are spaced apart slightly more than six inches so as to accommodate a standard small-metal-plate 10 that is six inches square. Side-blocks 22 are essentially parallel to each other and front-overlapping-retainer 24 has its opening essentially normal to the side-blocks 22. The inside height of front-overlapping-retainer 24 is slightly more than the expected thickness of a standard small-metal-plate 10. The typical small-metal-plate 10 has a centrally located, fixed-leg-coupler 12 that is perpendicular to the small-metal-plate 10 and typically fixed-leg-coupler 12 contains cross-pin-orifice 13 used with a cross-pin to retain the bottom of a scaffold leg, or the like. FIG. 4 shows an alternative coupler associated with small-metal-plate 10.

The permanent affixing of side-blocks 22 and front-overlapping-retainer 24 to the sill may be effected by welding, bolting, or other means such that the area between side-blocks 22 and front-overlapping-retainer 24 is kept clear to receive small-metal-plate 10. Welding is the preferred method of affixing side-blocks 22 and front-overlapping-retainer 24 to reusable mud-sill 30. An embodiment could be effected by casting or molding a single assembly that could include side-blocks 22, front-overlapping-retainer 24, and reusable mud-sill 30.

However constructed, the assembly consisting of side-blocks 22, front-overlapping-retainer 24, and reusable mud-sill 30 is augmented to accommodate moveable-rear-overlapping-retainer 32. The augmentation includes cutting (or otherwise effecting) a groove within reusable mud-sill 30 that will align with locking-lever's groove 39 when moveable-rear-overlapping-retainer 32 captures small-metal-plate 10 and that will receive locking-lever 38 when locking-lever 38 is rotated into a locking position. Optionally, one may augment the assembly consisting of side-blocks 22, front-overlapping-retainer 24, and reusable mud-sill 30 by providing spike-holes 42 in the corners of reusable mud-sill 30. Additional augmentation of the assembly consisting of side-blocks 22, front-overlapping-retainer 24, and reusable mud-sill 30 involves providing retaining-pins as described next.

Side-blocks 22 and front-overlapping-retainer 24 will retain small-metal-plate 10 in three horizontal directions, which includes sideways and upwards. Moveable-rear-overlapping-retainer 32 is used to affix small-metal-plate 10 in the fourth horizontal direction, and in the vertical direction, on a releasable basis. Moveable-rear-overlapping-retainer 32 and the mud-sill contain several cooperating parts. To effect the ability of the invention selectively to affix and to release small-metal-plate 10, moveable-rear-overlapping-retainer 32 is able captively to slide towards or away from the center of reusable mud-sill 30. The captive sliding capability is effected by extending two retaining-pins into retaining-pin's grooves 36 that are on each side of moveable-rear-overlapping-retainer 32 and that are parallel to each other. The above-surface ends of the retaining-pins are visible on the drawings as retaining-pin's heads 35. It is not possible to show the retaining-pins themselves as they are within retaining-pin's groove 36. The retaining-pins may be effected with bolts screwed down into the sill or with metal dowels extending upward through the sill. However effected, the retaining-pins have a width less than the width of retaining-pin's groove 36 and are surmounted with retaining-pin's head 35 that prevents moveable-rear-overlapping-retainer 32 from being detached from the mud-sill.

Alternatively, the preferred embodiment of the present invention may be described as an essentially flat-plate that is significantly larger than the small-metal-plate upon the top of which side-blocks 22, front-overlapping-retainer 24, and moveable-rear-overlapping-retainer 32 are placed. In the preferred embodiment, the essentially flat-plate is about 12 inches square and this size is included in what is meant by significantly larger than the small-metal-plate.

The side-blocks 22 are expected to be essentially parallel to each other, separated by slightly more than six inches, and having a height of at least twice the expected thickness of the small-metal-plate. Front-overlapping-retainer 24 is expected to be essentially normal to side-blocks 22 with an opening that faces towards the center of the flat-plate and that is slightly greater than the expected thickness of the conventional small-metal-plate. The moveable-rear-overlapping-retainer 32 is able captively to slide on the flat plate, has an opening that faces the opening of the front-overlapping-retainer 24, is essentially normal to side-blocks 22, and that is slightly greater than the expected thickness of the conventional small-metal-plate.

A rotatable locking-lever 38 is mounted on moveable-rear-overlapping-retainer 32 such that locking-lever 38 may be rotated into locking-lever's groove 39 that is within the flat-plate when the small-metal-plate is within and captured by moveable-rear-overlapping-retainer 32.

It is apparent that the flat-plate and its surmounted components may be made of steel and numerous other materials. It is also apparent that the shown, described and preferred side-blocks 22, front-overlapping-retainer 24, moveable-rear-overlapping-retainer 32 and its way of being captive and of being able to be locked, may be effected by other schemes that will apparent to one skilled in the art.

To use the present invention, one places reusable mud-sill 30 directly below a leg of a scaffold having a small-metal-plate 10, rotates locking-lever 38 out of engagement with locking-lever's groove 39 (and thus out of engagement with the cooperating groove in reusable mud-sill 30 that is not possible to be seen), slides moveable-rear-overlapping-retainer 32 away from the center of reusable mud-sill 30, places small-metal-plate 10 onto reusable mud-sill 30, slides an edge of small-metal-plate 10 under the overhang of front-overlapping-retainer 24, slides moveable-rear-overlapping-retainer 32 so that it overlaps small-metal-plate 10, and rotates locking-lever 38 into locking-lever's groove 39, thus capturing small-metal-plate 10. These steps are reversed when it is time to move the associated scaffolding and the reusable mud-sills 30. Optionally, one may place spikes 40 within spike-holes 42 so as to enhance the resistance of reusable mud-sill 30 to motion side-ways. Such spikes need not be driven flush with reusable mud-sill 30.

FIG. 2 shows the present invention with moveable-rear-overlapping-retainer 32 unlocked and moved towards the outer edge of the mud-sill so that reusable mud-sill 30 can receive small-metal-plate 10. FIG. 3 shows the present invention with moveable-rear-overlapping-retainer 32 moved away from the edge of the mud-sill so as to capture small-metal-plate 10 and FIG. 3 shows locking-lever 38 rotated about pivot-pin-support 34 using pivot-pin 37 to engage locking-lever's groove 39 and a groove below locking-lever's groove 39 that is in the mud-sill. FIG. 3 also shows that moveable-rear-overlapping-retainer 32 is kept from leaving the mud-sill by retaining-pin's heads 35 that are larger than the width of retaining-pin's groove 36.

The information in FIG. 4 differs from that in FIG. 3 only in that FIG. 4 shows the use of an optional, but conventional, way that small-metal-plate 10 is coupled to a leg of a scaffold. In FIG. 4, pivotable-scaffold-leg 15 has an upward section threaded and has its height adjustable by height-adjuster 18. Pivotable-scaffold-leg 15 is able to be pivoted from being perpendicular to small-metal-plate 10 by pivot-angle 19. That feature is effected by pivotable-scaffold-leg 15 having a lower cross-piece 16 normal to pivotable-scaffold-leg 15 that is captive within bushings 17. It is to be apparent that variations exist for effecting the coupling of the leg of a scaffold with small-metal-plate 10 and that reusable mud-sill 30 is able to capture the variations. Small-metal-plates 10 that are five inches square have been occasionally experienced and it has been found that the reusable mud-sill 30 described herein captures the smaller small-metal-plate 10 in a satisfactory manner. 

1. A reusable mud-sill for interfacing between ground and a conventional small-metal-plate at the bottom end of a scaffold leg, comprising: an essentially flat-plate that is significantly larger than the small-metal-plate; two side-blocks affixed to said flat-plate so as to be essentially parallel to each other and separated by slightly more than six inches; a front-overlapping-retainer affixed to said flat-plate having an opening that is essentially normal to said side-blocks, that faces towards the center of said flat-plate, and that is slightly greater than the thickness of the small-metal-plate; and a moveable-rear-overlapping-retainer slidably coupled to said flat-plate having an opening that is normal to said side-blocks, that is slightly greater than the thickness of the small-metal-plate, and that faces said opening of said front-overlapping-retainer, whereby the small-metal-plate can be captured between said side-blocks, and within said front-overlapping-retainer and said moveable-rear-overlapping retainer.
 2. A reusable mud-sill according to claim 1 wherein said essentially flat-plate is essentially 12 inches square.
 3. A reusable mud-sill according to claim 1 wherein said essentially flat-plate is composed of material selected from the group consisting of steel, stainless-steel, brass, aluminum, and plastic.
 4. A reusable mud-sill according to claim 1 wherein said essentially flat-plate is pierced by a plurality of spike-receiving orifices.
 5. A reusable mud-sill according to claim 1 wherein said side-blocks have a height of at least twice the thickness of the small-metal-plate.
 6. A reusable mud-sill according to claim 1 further including locking means associated with said moveable-rear-overlapping-retainer for preventing movement of said moveable-rear-overlapping-retainer when the small-metal-plate is within said moveable-rear-overlapping-retainer.
 7. A reusable mud-sill according to claim 6 further including effecting said locking means by: mounting a rotatable locking-lever on said moveable-rear-overlapping-retainer; effecting a groove in said flat plate for receiving said rotatable locking-lever; and rotating said rotatable locking-lever into said groove when the small-metal-plate is within said moveable-rear-overlapping-retainer.
 8. A reusable mud-sill communicating between ground and a conventional small-metal-plate at the bottom end of a scaffold leg, comprising: a steel plate that is significantly larger than the conventional small-metal-plate having a top, and a bottom; said bottom of said steel plate placed on the ground; parallel blocking means on said top of said steel plate for preventing movement of the small-metal-plate sideways when the small-metal-plate is placed on said rectangular steel plate; fixed captive means on said top of said steel plate, normal to said parallel blocking means, for receiving and overlapping an edge of the small-metal-plate thus preventing upward movement of the small-metal-plate; and slidable captive means on said top of said steel plate, normal to said parallel blocking means and facing said fixed captive means, for capturing an edge of the small-metal-plate when slid towards said fixed captive means, whereby the small-metal-plate is prevented from significant movement in all directions.
 9. A reusable mud-sill according to claim 8 further including locking means associated with said slidable captive means for preventing movement of said slidable captive means when said slidable captive means has captured an edge of the small-metal-plate.
 10. A reusable mud-sill according to claim 9 wherein said locking means is effected by: mounting a rotatable locking-lever on said slidable captive means; effecting a groove in said steel plate for receiving said rotatable locking-lever; and rotating said rotatable locking-lever into said groove when said slidable captive means has captured an edge of the small-metal-plate.
 11. A reusable mud-sill according to claim 8 wherein said rectangular steel plate is pierced by a plurality of spike-receiving orifices. 